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Tsirkin" , Sasha Levin Subject: [PATCH 6.6.y 2/2] hwrng: virtio - prevent use-after-free after a failed restore Date: Fri, 13 Nov 2026 23:22:35 -0500 Message-ID: <20261114042223.2847229-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261114042223.2847229-1-sashal@kernel.org> References: <20261109201257-failed-6.6-0f7bf47f5a0c@kernel.org> <20261114042223.2847229-1-sashal@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Thorsten Blum [ Upstream commit 0f7bf47f5a0cc26320aa4b14f4504d03a07f4b74 ] remove_common() frees the driver data during freeze, but does not clear vdev->priv, which points to freed memory. If probe_common() then fails during restore, a later remove or freeze can dereference the dangling pointer. Clear vdev->priv on the probe_common() error cleanup path and before freeing the driver data in remove_common(). Also reset the device and return early from remove_common() if vdev->priv is already NULL for a safe teardown after a failed restore. Fixes: 08e53fbdb85c ("virtio-rng: support multiple virtio-rng devices") Cc: stable@vger.kernel.org Signed-off-by: Thorsten Blum Reviewed-by: PrasannaKumar Muralidharan . Signed-off-by: Michael S. Tsirkin Message-ID: <20261016103640.4989-2-blum@kernel.org> Signed-off-by: Sasha Levin --- drivers/char/hw_random/virtio-rng.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index 65984504a3ca9..3b47bf1a65f51 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -187,6 +187,7 @@ static int probe_common(struct virtio_device *vdev) err_find: ida_free(&rng_index_ida, index); err_ida: + vdev->priv = NULL; kfree(vi); return err; } @@ -195,6 +196,11 @@ static void remove_common(struct virtio_device *vdev) { struct virtrng_info *vi = vdev->priv; + if (!vi) { + virtio_reset_device(vdev); + return; + } + vi->hwrng_removed = true; vi->data_avail = 0; vi->data_idx = 0; @@ -204,6 +210,7 @@ static void remove_common(struct virtio_device *vdev) virtio_reset_device(vdev); vdev->config->del_vqs(vdev); ida_free(&rng_index_ida, vi->index); + vdev->priv = NULL; kfree(vi); } -- 2.53.0